Put 1.5 liters of water in a saucepan. Add mustard, horseradish and bouillon and stir. Then cut the potatoes, 1 carrot and the celery into small pieces, add and cook until cooked.
The smoked mackerel is boned and added in small pieces. Add the parsley from the soup greens and plenty of dill. Bring to the boil, then you can serve.
The smoked mackerel pieces fray when they boil and bring a strong taste.